what happens when an electron returns to its ground stat from its excited state?

Answer 1

When an electron returns to the ground state, it loses the amount of energy that excited it, and emits a photon (electro-magnetic/light particle)

equation:
E=hc/l
h=Plancks constant 6.626x10^-34 N*m/s
c=speed of light 3x10^8 m/s
l =wavelength (if its 400-700nm, you will see the photon in color)
E=energy in J (N*m)

Answer 2

floor state: The electron is at its lowest available power point, and its closest generic distance from the nucleus. Excited state: The power is bigger than the floor state, and the generic distance from the nucleus is larger.